// Licensed to Apache Software Foundation(ASF) under one or more contributor
// license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright
// ownership. Apache Software Foundation(ASF) licenses this file to you under
// the Apache License, Version 2.0 (the "License"); you may
// not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

package event

// Observer pattern
// https://en.wikipedia.org/wiki/Observer_pattern
type Observer interface {
	Notify(event Event)
}

type Observable struct {
	Observers []Observer
}

func (self *Observable) RegistObserver(observer Observer) {
	self.Observers = append(self.Observers, observer)
}

func (self *Observable) UnregistObserver(observer Observer) {
	for index, ob := range self.Observers {
		if ob == observer {
			self.Observers = append(self.Observers[:index], self.Observers[index+1:]...)
			break
		}
	}
}

func (self Observable) NofityObservers(event Event) {
	for observer := range self.Observers {
		self.Observers[observer].Notify(event)
	}
}
